High pressure pump

ABSTRACT

A high-pressure pump is provided operating in a range from 50,000 p.s.i. to 100,000 p.s.i. but which is useful down to 3,000 p.s.i. in which packings at moving parts are eliminated and seal bushings are used, one toward the process fluid side and the other toward the atmosphere with a lubricating type fluid compatible with the fluid being pumped introduced between the bushings and tending to flow in both directions along the plunger. The pressure of the source of fluid is adjusted to control the clearance at the bushings. Static seals are provided at the outboard ends of each of the bushings to prevent the flow of the fluid except at the clearance locations. The leakage into the system and to the atmosphere is very small.

United States Patent Inventors Appl. No.

Filed Patented Assignee Rush B. Gunther Ablngton;

Robert C. Wolf, Hatboro, both 01, Pa.

Sept. 25, 1969 Aug. 31, 1971 The Duriron Company, Inc. Hatboro, Pa.

HIGH PRESSURE PUMP 5 Claims, 2 Drawing Figs.

Int. Cl Field of Search References Cited UNITED STATES PATENTS 1,850,6143/1932 Aisenstein Primary Examiner-Martin P. Schwadron AssistantExaminer-Clemens Schimikowski Attorney-Zachary T. Wobensmith, 2nd

ABSTRACT: A high-pressure pump is provided operating in a range from50,000 psi. to 100,000 p.s.i. but which is useful down to 3,000 p.s.i.in which packings at moving parts are eliminated and seal bushings areused, one toward the process fluid side and the other toward theatmosphere with a lubricating type fluid compatible with the fluid beingpumped introduced between the bushings and tending to flow in bothdirections along the plunger. The pressure of the source of fluid isadjusted to control the clearance at the bushings. Static seals areprovided at the outboard ends of each of the bushings to prevent theflow of the fluid except at the clearance locations. The leakage intothe system and to the atmosphere is very small.

PATENTED AUGSI I97! max/wars. RUSH B. GUNTHER ROBERT C. WOLF Af/Of/VZX AHIGH PRESSURE PUMP 1. Field of the Invention I This invention relates tohigh-pressure reciprocating pumps and more particularly to such pumpshaving spaced seal bushings on the pump plunger with a fluid introducedtherebetween and with controlled leakage of the fluid for lubricationand for the sealing of the plunger.

2. Description of the Prior Art In the production of polyethylene thecatalyst for use in converting ethylene into polyethylene is dispersedin a light hydrocarbon and pumped into the system at very highpressures. At an earlier period mineral oil which was much easier topump was used in place of the light hydrocarbons.

In the pumping of the water for high velocity cutting operations as wellas the production of polyethylene, pumping of fluids at pressures in therange from 50,000 to 100,000 p.s.i. is required. In pumping fluids atthese pressures, and particularly with reciprocating pumps, difficultieshave been encountered in connection with packing and seals employed toprevent leakage. Seals relying upon pressure applied thereto, includingspring loaded packing and glands tightened packing have not provensatisfactory because of the friction of the seal with the reciprocatingrod. Light hydrocarbons such as butane and hexane, and water aredifficult to pump because of their low viscosity and lack of lubricatingproperties at high pressures of the range stated.

As has been proposed, for rotating shafts, to provide spaced balancedpacking elements with pressure fluid introduced between the elements toprovide lubricant films between the elements and the rotating shaft, aspring urged soft packing was required to prevent leakage into thepressure vessel along the rotating shaft.

Reciprocation of the shaft or plunger as is required for a reciprocatingpump, with attendant friction of the packing and rod aggravates thedemands made on the soft packing and rapid destruction of the packing isinescapable.

SUMMARY OF THE INVENTION In accordance with the invention ahigh-pressure reciprocating pump is provided in which packing of thefriction type at the moving parts is eliminated, spaced rigid sealbushings being provided on the plunger, one toward the process fluidbeing pumped and the other toward the atmosphere with predetermineddiametrical clearances, and with a lubricating type fluid introducedunder pressure and at a pressure exceeding that of the process fluidbeing pumped, the fluid tending to leak through the clearances but beingcontrolled as to the rate of leakage by the orifices provided by theclearances. Static seals are provided at the exteriors of the sealbushings.

It is the principal object of the present invention to provide ahigh-pressure reciprocating pump having an improved character of plungerseal which does not require or employ friction packings at moving parts,which employs spaced orifice forming seal bushings on the plunger andwith fluid supplied therebetween with controlled leakage along theplunger at the orifices.

It is a further object of the present invention to provide ahigh-pressure reciprocating pump with provisions for sealing whichavoids friction and wear on packings engaging the plunger or othermoving parts, and thereby has a long useful life with a minimum ofmaintenance.

Other objects and advantageous features of the invention will beapparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic featuresof the invention will be more readily understood from the followingdescription taken in connection with the accompanying drawings formingpart thereof, in which:

FIG. 1 is a longitudinal sectional view of a high-pressure pump inaccordance with the invention, parts being shown diagrammatically, and

FIG. 2 is a transverse sectional view taken approximately on the line2--2 of FIG. 1

It should, of course, be understood that the description and drawingsherein are illustrative merely, and that various modificationsandchanges can be made in the structure disclosed without departing fromthe spirit of the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularlyto the drawings, a highpressure reciprocating pump in accordance withthe invention is there shown at 10, with a cylinder 11, mounted in apumpframe 12 in any desired manner such as by a threaded connection 13.

The cylinder 11 has a longitudinal cylindrical bore 14 with a nut 15 atthe operating end having a threaded connection 16 to the cylinder 11.The nut 15 has a cylindrical portion l7 which extends into the bore 14.The cylinder 11 at the liquid pumping end, is closed by a cover 18 whichhas a cylindrical portion 19 extending into the bore 14 and a head 20extending radially outwardly at the end of the cylinder 11. The cover 18is secured to the cylinder 11 in any desired manner, such as by studs(not shown).

The cover 18 has a T-shaped passageway 21 therein communicating with thebore 14, one branch 22 of the passageway 21 having inlet or suctioncheck valve 23, illustrated diagrammatically mounted therein foradmission of process fluid. Another branch 24 of the passageway 21 has adischarge check valve 25, illustrated diagrammatically mounted thereinfor the delivery of the process fluid.

A plunger 28 is provided, engaged in a socket 29 in a plunger holder 30and held in the socket 29 by a split ring 31. The plunger holder 30 isreciprocated in any desired manner, such as by a crank and crosshead(not shown).

The plunger 28 extends through a central opening in the nut 15. Withinthe bore 14 outer and inner seal bushings 33 and 34 are provided. Thebushings 33 and 34 are held in spaced relation by a spaced ring 35having an outer circumferential passageway 36, an inner circumferentialpassageway 37 and radial connecting passageways 38.

The outer seal bushing 33 has an inner bore 39 and an outercircumferential end groove 40 with a terminal wall portion 41 whichincludes a curved face 42.

Disposed within the groove 40 and engaging the wall portion 41 and face42 a static seal ring 44- is provided, of 1:. r cross section, forsealing engagement with the bore i compression and retaining ring 45 inthe groove 40 is urg i into seal effecting engagement with the seal ring44 by the portion 17.

The inner seal bushing 34 is similar to the outer seal bushing 33, hasan inner bore 47 and an outer circumferential endgroove 48 with aterminal wall portion 49 which includes a curved face 50.

Disposed within the groove 48 and engaging the wall portion 49 and face50, static seal ring 51 is provided of circular cross section forsealing engagement with the bore 14. A compression and retaining ring 52in the groove 48 is urged into seal effecting engagement with the sealring 51 by a filler piece 54 of hollow cylindrical configuration whichis disposed in the bore 14 and has a central longitudinal opening 55within which the plunger 28 is longitudinally movable.

The cover portion 19 has an outer circumferential end groove 57 with aterminal end wall portion 58 which includes a curved face 59.

Disposed within the groove 57 and engaging the wall portion 58 and face59, a static seal ring 60 is provided of circular cross section, forsealing engagement with the bore 14. A compression and retainer ring 61in the groove 57 is urged into seal effecting engagement with the sealring 60 by the engagement of the tiller piece 54 therewith.

The seal bushings 33 and 34 are preferably made of cast iron, bronze,tungsten carbide, aluminum oxide or other suitable materials selectedfor their antigalling properties.

Tungsten carbide is preferred because of its stiffness which reduces theratio of the outside diameter to the inside diame ter of the bushings 33and 34. The reduction in spaced for higher pressure use is desirablesince lower modulus materials result in undue thickness.

The inner bore 39 of the bushing 33, and the inner bore 47 of thebushing 34 and the exterior diameter of the plunger 28 are such thatwhen fluid pressure is applied on the bushings 33 t and 34 as isexplained below, a predetermined orifice size or clearance will beprovided. Typical, diametrical clearances are from five ten-thousandthsto one one-thousandth of an inch.

The seal rings 44, 51 and 60 are of metal such as cast iron, bronze ortungsten carbide to withstand a wide range of oscillating fluid pressurethereon which may range from a suction pressure of the process fluid of30 to 50 p.s.i. to the delivered pressure of 50,000 p.s.i. or higher.

The cylinder 11 has a passageway 65 in communication with the bore 14 atthe location of the passageway 36 of the spaced ring 35 with which afluid connection 66 is connected. A reservoir 67 is connected through aninlet check valve 68, pumps 70 and delivery check valve 71 to the fluidconnection 66.

A seal fluid compatible with the process fluid being pumped and capableof providing a hydrodynamic film of lubrication at the bores 39 and 47is provided in the reservoir 67 and the pump 70 is operated to supplythe fluid from the reservoir 67 between the bushings 33 and 34 at apressure which is in excess of the delivery pressure of the processfluid being pumped.

The cylinder 11, at the inner end of the threaded connection 16 ispreferably provided with weep holes 73 for discharge of any fluidleaking to this location and indicative of leakage at the seal ring 60.

The frame 12, exteriorly of the U-nut 15 is preferably provided withweep holes 74 for discharge of any fluid leaking to this location andindicating the effectiveness of the controlled leakage to this location.

Upon reciprocation of the plunger 28, process fluid entering through thecheck valve 23 will be discharged at increased pressure through thecheck valve 25 which delivery pressure can be of the order of 50,000 to100,000 p.s.i.

The seal ring 60 prevents leakage of the process fluid from the bore 14between the cover portion 19 and the cylinder 11.

The seal ring 51 prevents leakage of the process fluid from the bore 14between the seal ring 34 and the cylinder 11 and prevents the seal fluidfrom leakage at this location.

The seal ring 44 prevents leakage of seal fluid at this location.

The seal fluid delivered from the pump 70 is preferably at a constantpressure and upon its delivery through the fluid connection 66 and fluidpassageway 67 is effective in both directions on the exteriors of thebushings 33 and 34 causing them to reduce the original clearance whichexisted at the bores 39 and 47 and along the plunger 28 at these bores.A limited quantity of the seal fluid is pennitted to flow along theplunger 28 in each direction from the spacer ring 35 and the orificesprovided by the clearances between the plunger 28 and the seal bushings33 and 34 at the bores 39 and 47. A portion of the seal fluid will beintroduced into the process fluid,

the seal fluid as previously mentioned being selected to be compatibletherewith. A portion of the seal fluid will escape and its dischargewill be observable at the weep openings 74.

The delivery pressure of fluid from the pump 70 can be adjusted tocontrol these clearances. Increasing the pressure will eneration atthese locations is minimal. Cooling as required or conventional packingsis rendered unnecessary although it could be employed if the processfluid is of such temperature level as to render it desirable.

The leakage is preferably controlled so that it amounts only to a fewcubic centimeters per hour.

It will thus be seen that the pump has been provided which attains theobjects of the invention.

We claim:

1. A pump comprising a cylinder having a continuous longitudinal borewith a working end and a process fluid pumping end,

fluid inlet and delivery valves for said pumping end of said cylinder,

a plunger reciprocable in said cylinder,

axially disposed seal bushings in said cylinder bore and intermediatesaid cylinder ends and each having interior bores within which saidplunger is movable,

a clearance between said plunger and said interior bores of said bushingproviding orifices for fluid lubricant delivery towards said ends ofsaid interior bores,

means for supplying fluid lubricant under orifices,

a seal supporting member at the working end of said cylinder and throughwhich said plunger is reciprocable, said seal support member having atransverse face with which one end of one of said seal bushings is inengagement,

a static seal at said end of said seal bushing contiguous to said sealsupporting member between the exterior of said seal bushing and saidcylinder bore,

said process fluid pumping end of said bore being closed by an end covermember,

a hollow cylindrical filler member in said cylinder bore between and inengagement 17 cover with said cover member and the other of said sealbushings and in the interior of which said plunger is reciprocable, and

a static seal at the end of said other seal bushing contiguous to saidfiller member between the exterior of said other seal bushing and saidcylinder bore.

2. A pump as defined in claim 1 in which said seal supporting member isa nut and said nut is engaged with said cylinder.

3. A pump as defined in claim 1 in which said end cover member has aportion extending into said bore.

4. A pump as defined in claim 3 in which a static seal is providedbetween said portion of said end cover member and said bore.

5. A pump as defined in claim 1 in which said means supplying fluidunder pressure includes a member delivering fluid at a pressure higherthan the delivered pressure of the process fluid.

pressure to said UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent N 3 602 613 Dated August 31, 1971 Inventor(s) Rush B. GunterRobert C. Wolf It: is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Claim 1, column 4 line 45 after "engagement" delete -17 cover- Signedand sealed this 11th day of January 1972'.

( SEAL Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHMJK I attesting Officer ActingCommissioner of Patents RM (1059] USCOMM-DC 60376-P69 Q UI5 GOVERNMENTPRINTING OFFICE IDD O3GG-3Jl

1. A pump comprising a cylinder having a continuous longitudinal borewith a working end and a process fluid pumping end, fluid inlet anddelivery valves for said pumping end of said cylinder, a plungerreciprocable in said cylinder, axially disposed seal bushings in saidcylinder bore and intermediate said cylinder ends and each havinginterior bores within which said plunger is movable, a clearance betweensaid plunger and said interior bores of said bushing providing orificesfor fluid lubricant delivery towards said ends of said interior bores,means for supplying fluid lubricant under pressure to said orifices, aseal supporting member at the working end of said cylinder and throughwhich said plunger is reciprocable, said seal support member having atransverse face with which one end of one of said seal bushings is inengagement, a static seal at said end of said seal bushing contiguous tosaid seal supporting member between the exterior of said seal bushingand said cylinder bore, said process fluid pumping end of said borebeing closed by an end cover member, a hollow cylindrical filler memberin said cylinder bore between and in engagement 17 cover with said covermember and the other of said seal bushings and in the interior of whichsaid plunger is reciprocable, and a static seal at the end of said otherseal bushing contiguous to said filler member between the exterior ofsaid other seal bushing and said cylinder bore.
 2. A pump as defined inclaim 1 in which said seal supporting member is a nut and said nut isengaged with said cylinder.
 3. A pump as defined in claim 1 in whichsaid end cover member has a portion extending into said bore.
 4. A pumpas defined in claim 3 in which a static seal is provided between saidportion of said end cover member and said bore.
 5. A pump as defined inclaim 1 in which said means supplying fluid under pressure includes amember delivering fluid at a pressure higher than the delivered pressureof the process fluid.